Green chemistry: biomass polymers
Biomass and the 12 principles of green chemistry
The past five decades have been a period of unprecedented transformations involving lifestyles around the world. Many of the key changes in society are the result of numerous advances in science and technology. These technological and social developments interact with each other and add up with often undesirable consequences from the point of view of energy consumption, ecological, and environmental degradation.
In the field of the chemical industry, the strategic challenge for the twenty-first century is the need to develop renewable raw materials to replace those coming from oil. In this context, the use of plant biomass can be considered as an alternative to the use of more polluting raw materials. And it can also become an important economic value for aggro-industrial chains.
In the 90s, Green Chemistry emerged based on 12 principles, a new philosophy that has a holistic view of the production processes of the chemical industry. The movement involved both the academic and industrial worlds who wanted to break the old paradigms of chemistry as a generator of large quantities of waste and the intensive use of petrochemicals.
Plant biomass, and in general the use of renewable raw materials, offers a great strategic opportunity for many industrial production segments.
A wide range of chemicals, especially organic ones such as acids, esters, alcohols, sugars or phenol's, can be extracted from plant biomass. Basically four types of biomass of great economic interest can be classified:
- oil seeds, mainly from soy and palm oil
- sugars, saccharides from sugar cane and sorghum
- starchy, from corn
- lignocellulosic, such as straw and wood.
The heterogeneity and consequent chemical complexity of plant biomass, in turn, requires innovative processes to make the entire supply chain and final products truly sustainable, as indicated in the 12 principles for the green chemical industry.
The 12 fundamental principles of green chemistry
The concept of green chemistry saw the light in 1998 when Paul Anastas and John Warner published the book Green Chemistry: Theory and Practice. Here the two chemists define the fundamental concepts and methods for the first time.
- Prevention: it is better to prevent the production of waste and scraps upstream, rather than treating and reclaiming them once created.
- Atomic economy: the chemical reactions of synthesis must be designed trying to maximize the incorporation of all the atoms of the initial reagents in the final products.
- Less dangerous chemical syntheses: where possible, the synthesis methods must be designed using and generating substances that are little or not at all toxic to humans and the environment.
- Design of safer chemical products: we must try to design chemical products functional to their use, minimizing toxicity.
- Safer solvents and additives: the use of solvents and separation agents must be avoided or limited as much as possible. If used, they must be harmless.
- Energy efficiency: the energy demand for chemical processes must be evaluated and minimized taking into account its environmental and economic impact.
- Use of renewable raw materials: as far as feasible from a technical and economic point of view, the raw materials must be renewable.
- Reduce derivatives: we must minimize or eliminate the production of unnecessary derivatives and not produce waste or reduce the synthetic steps to get to the product.
- Catalysis: catalysts can facilitate a reaction in different ways, for example by accelerating it or increasing its yield.
- Degradation: the chemicals that are designed must be able to decompose easily at the end of their life cycle, so as not to persist in the environment.
- Real-time analysis to prevent pollution: prevent the formation of hazardous substances with monitoring and control methods during a process.
- Safety: substances and formulations must be chosen that allows to minimize the risk of accidents. Put the safety of workers and the health of the people who use the products first.
These concepts are especially welcomed in countries with the well-developed chemical industry and strict controls on the emission of pollutants. Experimental projects are giving rise to industrial productions that replace the most polluting and harmful ones.
Applications of biomass for the production of chemicals
Biomass fully complies with the seventh principle on the use of renewable raw materials. A further step towards sustainability and the circular economy is the recovery of organic waste fractions that do not subtract crops for human or animal nutrition. Waste is the visible consequence of a production and consumption system that does not work and that is causing serious damage to the planet's ecosystem. The European Union alone produces over 100 million tons of organic waste and these are incinerated or buried. Recovery avoids the release of CO₂ into the air or the harmful leachate that pollutes groundwater and soil.
To follow this path, Covestro adheres to and promotes experimental projects to find new ways of sustainability.
Organic urban waste
Since 2017 Covestro has participated in the EU-funded PERCAL project. The project intends to exploit the organic fraction of urban waste to extract precious chemical products suitable for use in production chains.
Three paths have been identified
- to produce lactic acid for ecological solvents of ethyl lactate by reactive distillation from lactic acid and bioethanol. This can be used in cleaning products, inks, and hot-melt adhesives for a carton.
- obtaining succinic acid to be used in the production of polyols for the polyurethane of the products from stuffing.
- obtain biosurfactants by chemical and/or microbiological modification of the protein and lipid fraction that remains from the fermentation process of urban waste. Surfactants can be used in cleaning products.
The ninth principle of Green Chemistry establishes the need to search for new catalysts to make processes more efficient. Oxidative enzymes have not yet registered a complete change in the biobased industries and there is still room for improving the economic and environmental sustainability of bio-refineries. This is why the SMARTBOX project was born, funded by the EU, which involves production companies such as Covestro and academic research bodies. The project aims to develop a specific computational engineering platform for oxidative enzymes and implemented it with artificial intelligence. Through the use of renewable raw materials coming from processing waste such as lignin, cellulose or wood remains, Covestro and its partners are working to obtain a new building block from biomass for the production of high-performance plastic poly-carbonates.
A third project called BioCatPolymers involves production subjects such as Covestro and various European countries. The goal is to find a sustainable and efficient technological path to convert the residual biomass of wood processing into bio polymers with high added value. The technology is based on an integrated hybrid bio-thermochemical process. The biological step consists of the efficient conversion of sugars derived from biomass into mevalonolactone (MVL). MVL can then be converted into bio-monomers by highly selective chemo-catalytic processes. The entire process aims at the efficient and economical production of isoprene and 3-methyl 1,5-pentanediol (3MPD), two monomers that have very large markets that can be used in the production of elastomers and polyurethanes that are currently fossil-based. It has been calculated that the full production of bio-isoprene will have a cost reduction of 50% while it reaches 70% for 3MPD, thus increasing the competitiveness of biological processes in terms of economy.
Circular economy and biomass
Industrial ecology, green chemistry, and the use of biomass are closely related to improving the environmental aspects of production processes and promoting their sustainability. 100 years have passed since, in 1920, Hermann Staudinger discovered the first polymers, which then forcefully entered daily life. Since then, many steps remain to be taken in terms of discoveries and new challenges. One of these is to work on innovative and economically sustainable processes. Only a #pushing boundaries attitude can pave the way for the circular economy that knows how to combine growth, well-being, and the environment.